Antibodies have been widely used in various fields including biotechnology, pharmaceuticals, and foods. Each antibody has its own activity. Based on their activity, antibodies are selected for use for different purposes. Various methods are known for producing antibodies, and mass production of desired antibodies is also possible.
However, known production methods do not always produce antibodies with sufficient activity. For example, most antibodies are often inactive when produced with the use of recombinant Escherichia coli or the like as a host. To obtain antibodies with desired activity, a refolding operation must further be performed with respect to the obtained inactive antibodies.
In relation to refolding, a method for refolding a denatured protein has been reported, comprising adding a denatured protein dropwise to a refolding buffer containing, for example, arginine, reduced glutathione, and oxidized glutathione (Patent Literature (PTL) 1). A method comprising the step of refolding a membrane protein in the presence of a surfactant has also been reported (Patent Literature (PTL) 2). There is also a report stating that after a peptide having an anchoring part that binds to an activated solid phase was allowed to adsorb onto the solid-phase surface by chelate bonding, wherein the activated solid phase contains metal ions that are coordinatively bound to metal-chelating ligands, refolding of this peptide was successfully performed on the solid-phase surface (Patent Literature (PTL) 3). There is also a report stating that after a specific peptide was allowed to adsorb onto a solid-phase surface, the steric structure of the peptide was successfully reconstructed on the solid-phase surface (Patent Literature (PTL) 4 and Patent Literature (PTL) 5).
As described above, various refolding methods have thus far been reported. However, the refolding efficiency is low in these known methods.